Field of Invention
The present invention relates to a wireless access system, and more particularly, to a method and apparatus for transmitting uplink channel information (UCI) including channel quality control information in a carrier aggregation environment (i.e., a multi-component carrier environment). The invention relates to a method and apparatus for obtaining the number of resource elements allocated to UCI when the UCI piggybacks on a physical uplink shared channel (PUSCH).
Discussion of the Related Art
A 3GPP LTE (3rd Generation Partnership Project Long Term Evolution; Rel-8 or Rel-9) system (hereinafter referred to as an LTE system) employs multi-carrier modulation (MCM) that splits a single component carrier (CC) into multiple bands and uses the multiple bands. However, a 3PP LTE-Advanced system (hereinafter referred to as an LTE-A system) can use carrier aggregation (CA) that aggregates one or more CCs to support a system bandwidth wider than that of the LTE system. The CA can be replaced by carrier matching, multi-CC environment, or multi-carrier environment.
In a single CC environment such as an LTE system, a description is made of only a case in which uplink control information (UCI) and data are multiplexed using a plurality of layers on one CC.
In a CA environment, however, one or more CCs can be used and the number of pieces of UCI can be increased to a multiple of the number of CCs. For example, while rank indication information has 2 or 3 bits in the LTE system, it can have a maximum of 15 bits in the LTE-A system since the bandwidth can be extended to up to 5 CCs.
In this case, UCI having a size of 15 bits cannot be transmitted using a UCI transmission method defined in the LTE system and cannot be encoded even when Reed-Muller (RM) code is used. Accordingly, the LTE-A system needs a new method for transmitting UCI having a large size.